Our purpose is to gather comprehensive epidemiological data on 310 "atypical schizophrenics" in a longterm follow-up and family study. Procedures designed in the Iowa 500 Research Project, a study of the major psychoses now nearing completion at University of Iowa Psychiatric Hospital (IPH), give us highly effective methods for tracing and personally interviewing subjects as well as extensive procedures for data management and analysis. In the Iowa 500 study, we used specified research criteria to select nuclear groups of 200 schizophrenics, 100 manics, and 225 depressives from patients consecutively admitted to IPH between 1934-1944. In the same population, 310 carried a chart diagnosis of schizophrenia but failed to meet the research criteria, chiefly for short duration of symptoms, episodic course, or mixed schizophrenic and affective symptoms. These 310 atypical schizophrenics and their families, plus a stratified random sample of 176 surgical controls and their families comprise the study sample. The control group provides a baseline for comparison and maintains blindness in data collection. Our aim is to identify homogeneous subgroups within the atypical schizophrenics by analyzing all follow-up and family data. We will compare these subgroups with any homogeneous subgroups we identify within the typical groups of schizophrenia and affective disorder. Using all available information we will identify homogeneous subgroups within the major psychoses. Finally, we hope to use the results of our analysis to refine the research criteria for selecting pure subgroups in future biological and psycho-social studies.